1. Field of the Invention
The present invention relates to a steering system for automobiles and, more particularly, to a steering system of automobiles for absorbing impact energy when force is generated from the collision in order to lessen the impact force to the driver.
2. Description of the Conventional Art
In general, the steering by the driver is transmitted to a steering tube and a steering shaft in the conventional steering systems for automobiles.
During the collision, the driver collides with the steering wheel caused by the inertia. In response to the collision, there is a reaction force in which the driver is more severely injured.
In order to absorb the impact energy and lessen the impact to the driver, the steering shaft that slides into the steering tube that is connected to the steering wheel has been developed.
FIG. 1 shows the structure of a conventional steering system which has been developed to lessen the impact to the driver during the collision.
In FIG. 1, the steering system comprises an outer tube 12, an inner tube 14, and balls 22, 24 which are inserted between the outer tube 12 and the inner tube 14. Further, grooves 26 are formed on the outer surface of the inner tube 14 for guiding the balls 22 and 24.
In the above structure, the number of the grooves 26 is less than the number of the balls 22 and 24 so that the impact force is absorbed by the remaining balls which are not introduced into the grooves. When the inner tube 14 slides into the outer tube 12 by the impact force applied to a steering wheel(not shown) at the time of the collision, the balls 22 and 24 located between the outer tube 12 and the inner tube 14 move and absorb the impact force by frictional force generated by the movement of the balls.
In FIG. 1, number 20 indicates a sleeve, and number 28 indicates a slanted wall.
However, the conventional steering system described above has disadvantages that the steering system absorbs the impact force uniformly regardless of the magnitude of the impact force, so that it is difficult to disperse the repulsive force to the driver.
The balls 24 absorb the impact force uniformly from the beginning to the end of the collision, hence the repulsive force can not be dispersed effectively and the driver would not have enough time to react to the collision. Hence, it is difficult to prevent the driver from being injured from the repulsive force generated by the impact.